1 module CmmBuildInfoTables
2 ( CAFSet, CAFEnv, CmmTopForInfoTables(..), cafAnal, localCAFInfo, mkTopCAFInfo
3 , setInfoTableSRT, setInfoTableStackMap
4 , TopSRT, emptySRT, srtToData
6 , finishInfoTables, lowerSafeForeignCalls, extendEnvsForSafeForeignCalls )
9 #include "HsVersions.h"
13 import qualified Prelude as P
20 import Cmm hiding (blockId)
33 import MkZipCfgCmm hiding (CmmAGraph, CmmBlock, CmmTopZ, CmmZ, CmmGraph)
43 import ZipCfg hiding (zip, unzip, last)
44 import qualified ZipCfg as G
48 ----------------------------------------------------------------
49 -- Building InfoTables
52 -----------------------------------------------------------------------
55 -- Given a block ID, we return a representation of the layout of the stack,
56 -- as suspended before entering that block.
57 -- (For a return site to a function call, the layout does not include the
58 -- parameter passing area (or the "return address" on the stack)).
59 -- If the element is `Nothing`, then it represents a word of the stack that
60 -- does not contain a live pointer.
61 -- If the element is `Just` a register, then it represents a live spill slot
62 -- for a pointer; we assume that a pointer is the size of a word.
63 -- The head of the list represents the young end of the stack where the infotable
64 -- pointer for the block `Bid` is stored.
65 -- The infotable pointer itself is not included in the list.
66 -- Call areas are also excluded from the list: besides the stuff in the update
67 -- frame (and the return infotable), call areas should never be live across
70 -- RTS Invariant: All pointers must be word-aligned because each bit in the bitmap
71 -- represents a word. Consequently, we have to be careful when we see a live slot
72 -- on the stack: if we have packed multiple sub-word values into a word,
73 -- we have to make sure that we only mark the entire word as a non-pointer.
75 -- Also, don't forget to stop at the old end of the stack (oldByte),
76 -- which may differ depending on whether there is an update frame.
77 live_ptrs :: ByteOff -> BlockEnv SubAreaSet -> AreaMap -> BlockId -> [Maybe LocalReg]
78 live_ptrs oldByte slotEnv areaMap bid =
79 -- pprTrace "live_ptrs for" (ppr bid <+> ppr youngByte <+> ppr liveSlots) $
80 reverse $ slotsToList youngByte liveSlots []
81 where slotsToList n [] results | n == oldByte = results -- at old end of stack frame
82 slotsToList n (s : _) _ | n == oldByte =
83 pprPanic "slot left off live_ptrs" (ppr s <+> ppr oldByte <+>
84 ppr n <+> ppr liveSlots <+> ppr youngByte)
85 slotsToList n _ _ | n < oldByte =
86 panic "stack slots not allocated on word boundaries?"
87 slotsToList n l@((n', r, w) : rst) results =
88 if n == (n' + w) then -- slot's young byte is at n
89 ASSERT (not (isPtr r) ||
90 (n `mod` wORD_SIZE == 0 && w == wORD_SIZE)) -- ptrs must be aligned
91 slotsToList next (dropWhile (non_ptr_younger_than next) rst)
93 else slotsToList next (dropWhile (non_ptr_younger_than next) l)
95 where next = n - wORD_SIZE
96 stack_rep = if isPtr r then Just r else Nothing
97 slotsToList n [] results = slotsToList (n - wORD_SIZE) [] (Nothing : results)
98 non_ptr_younger_than next (n', r, w) =
100 ASSERT (not (isPtr r))
102 isPtr = isGcPtrType . localRegType
103 liveSlots = sortBy (\ (off,_,_) (off',_,_) -> compare off' off)
104 (foldFM (\_ -> flip $ foldl add_slot) [] slots)
106 add_slot rst (a@(RegSlot r@(LocalReg _ ty)), off, w) =
107 if off == w && widthInBytes (typeWidth ty) == w then
108 (expectJust "add_slot" (lookupFM areaMap a), r, w) : rst
109 else panic "live_ptrs: only part of a variable live at a proc point"
110 add_slot rst (CallArea Old, _, _) =
111 rst -- the update frame (or return infotable) should be live
112 -- would be nice to check that only that part of the callarea is live...
113 add_slot rst ((CallArea _), _, _) =
115 -- JD: THIS ISN'T CURRENTLY A CORRECTNESS PROBLEM, BUT WE SHOULD REALLY
116 -- MAKE LIVENESS INFO AROUND CALLS MORE PRECISE -- FOR NOW, A 32-BIT
117 -- FLOAT PADS OUT TO 64 BITS, BUT WE ASSUME THE WHOLE PARAMETER-PASSING
118 -- AREA IS LIVE (WHICH IT ISN'T...). WE SHOULD JUST PUT THE LIVE AREAS
119 -- IN THE CALL NODES, WHICH SHOULD EVENTUALLY HAVE LIVE REGISTER AS WELL,
120 -- SO IT'S ALL GOING IN THE SAME DIRECTION.
121 -- pprPanic "CallAreas must not be live across function calls" (ppr bid <+> ppr c)
122 slots = expectJust "live_ptrs slots" $ lookupBlockEnv slotEnv bid
123 youngByte = expectJust "live_ptrs bid_pos" $ lookupFM areaMap (CallArea (Young bid))
125 -- Construct the stack maps for the given procedure.
126 setInfoTableStackMap :: SlotEnv -> AreaMap -> CmmTopForInfoTables -> CmmTopForInfoTables
127 setInfoTableStackMap _ _ t@(NoInfoTable _) = t
128 setInfoTableStackMap slotEnv areaMap t@(FloatingInfoTable _ bid updfr_off) =
129 updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
130 setInfoTableStackMap slotEnv areaMap
131 t@(ProcInfoTable (CmmProc (CmmInfo _ _ _) _ _ ((_, Just updfr_off), _)) procpoints) =
132 case blockSetToList procpoints of
133 [bid] -> updInfo (const (live_ptrs updfr_off slotEnv areaMap bid)) id t
134 _ -> panic "setInfoTableStackMap: unexpected number of procpoints"
135 -- until we stop splitting the graphs at procpoints in the native path
136 setInfoTableStackMap _ _ t = pprPanic "unexpected case for setInfoTableStackMap" (ppr t)
140 -----------------------------------------------------------------------
143 -- WE NEED AN EXAMPLE HERE.
144 -- IN PARTICULAR, WE NEED TO POINT OUT THE DISTINCTION BETWEEN
145 -- FUNCTIONS WITH STATIC CLOSURES AND THOSE THAT MUST BE CONSTRUCTED
146 -- DYNAMICALLY (AND HENCE CAN'T BE REFERENCED IN AN SRT).
147 -- IN THE LATTER CASE, WE HAVE TO TAKE ALL THE CAFs REFERENCED BY
148 -- THE CLOSURE AND INLINE THEM INTO ANY SRT THAT MAY MENTION THE CLOSURE.
149 -- (I.E. TAKE THE TRANSITIVE CLOSURE, but only for non-static closures).
152 -----------------------------------------------------------------------
153 -- Finding the CAFs used by a procedure
155 type CAFSet = FiniteMap CLabel ()
156 type CAFEnv = BlockEnv CAFSet
158 -- First, an analysis to find live CAFs.
159 cafLattice :: DataflowLattice CAFSet
160 cafLattice = DataflowLattice "live cafs" emptyFM add False
161 where add new old = if sizeFM new' > sizeFM old then aTx new' else noTx new'
162 where new' = new `plusFM` old
164 cafTransfers :: BackwardTransfers Middle Last CAFSet
165 cafTransfers = BackwardTransfers first middle last
166 where first _ live = live
167 middle m live = foldExpDeepMiddle addCaf m live
168 last l env = foldExpDeepLast addCaf l (joinOuts cafLattice env l)
169 addCaf e set = case e of
170 CmmLit (CmmLabel c) -> add c set
171 CmmLit (CmmLabelOff c _) -> add c set
172 CmmLit (CmmLabelDiffOff c1 c2 _) -> add c1 $ add c2 set
174 add l s = if hasCAF l then addToFM s (cvtToClosureLbl l) () else s
176 type CafFix a = FuelMonad (BackwardFixedPoint Middle Last CAFSet a)
177 cafAnal :: LGraph Middle Last -> FuelMonad CAFEnv
178 cafAnal g = liftM zdfFpFacts (res :: CafFix ())
179 where res = zdfSolveFromL emptyBlockEnv "live CAF analysis" cafLattice
180 cafTransfers (fact_bot cafLattice) g
182 -----------------------------------------------------------------------
185 -- Description of the SRT for a given module.
186 -- Note that this SRT may grow as we greedily add new CAFs to it.
187 data TopSRT = TopSRT { lbl :: CLabel
188 , next_elt :: Int -- the next entry in the table
189 , rev_elts :: [CLabel]
190 , elt_map :: FiniteMap CLabel Int }
191 -- map: CLabel -> its last entry in the table
192 instance Outputable TopSRT where
193 ppr (TopSRT lbl next elts eltmap) =
194 text "TopSRT:" <+> ppr lbl <+> ppr next <+> ppr elts <+> ppr eltmap
196 emptySRT :: MonadUnique m => m TopSRT
198 do top_lbl <- getUniqueM >>= \ u -> return $ mkSRTLabel (mkFCallName u "srt") NoCafRefs
199 return TopSRT { lbl = top_lbl, next_elt = 0, rev_elts = [], elt_map = emptyFM }
201 cafMember :: TopSRT -> CLabel -> Bool
202 cafMember srt lbl = elemFM lbl (elt_map srt)
204 cafOffset :: TopSRT -> CLabel -> Maybe Int
205 cafOffset srt lbl = lookupFM (elt_map srt) lbl
207 addCAF :: CLabel -> TopSRT -> TopSRT
209 srt { next_elt = last + 1
210 , rev_elts = caf : rev_elts srt
211 , elt_map = addToFM (elt_map srt) caf last }
212 where last = next_elt srt
214 srtToData :: TopSRT -> CmmZ
215 srtToData srt = Cmm [CmmData RelocatableReadOnlyData (CmmDataLabel (lbl srt) : tbl)]
216 where tbl = map (CmmStaticLit . CmmLabel) (reverse (rev_elts srt))
218 -- Once we have found the CAFs, we need to do two things:
219 -- 1. Build a table of all the CAFs used in the procedure.
220 -- 2. Compute the C_SRT describing the subset of CAFs live at each procpoint.
222 -- When building the local view of the SRT, we first make sure that all the CAFs are
223 -- in the SRT. Then, if the number of CAFs is small enough to fit in a bitmap,
224 -- we make sure they're all close enough to the bottom of the table that the
225 -- bitmap will be able to cover all of them.
226 buildSRTs :: TopSRT -> FiniteMap CLabel CAFSet -> CAFSet ->
227 FuelMonad (TopSRT, Maybe CmmTopZ, C_SRT)
228 buildSRTs topSRT topCAFMap cafs =
229 do let liftCAF lbl () z = -- get CAFs for functions without static closures
230 case lookupFM topCAFMap lbl of Just cafs -> z `plusFM` cafs
231 Nothing -> addToFM z lbl ()
232 sub_srt topSRT localCafs =
233 let cafs = keysFM (foldFM liftCAF emptyFM localCafs)
235 do localSRTs <- procpointSRT (lbl topSRT) (elt_map topSRT) cafs
236 return (topSRT, localSRTs)
237 in if length cafs > maxBmpSize then
238 mkSRT (foldl add_if_missing topSRT cafs)
239 else -- make sure all the cafs are near the bottom of the srt
240 mkSRT (add_if_too_far topSRT cafs)
241 add_if_missing srt caf =
242 if cafMember srt caf then srt else addCAF caf srt
243 -- If a CAF is more than maxBmpSize entries from the young end of the
244 -- SRT, then we add it to the SRT again.
245 -- (Note: Not in the SRT => infinitely far.)
246 add_if_too_far srt@(TopSRT {elt_map = m}) cafs =
247 add srt (sortBy farthestFst cafs)
249 farthestFst x y = case (lookupFM m x, lookupFM m y) of
250 (Nothing, Nothing) -> EQ
251 (Nothing, Just _) -> LT
252 (Just _, Nothing) -> GT
253 (Just d, Just d') -> compare d' d
255 add srt@(TopSRT {next_elt = next}) (caf : rst) =
256 case cafOffset srt caf of
257 Just ix -> if next - ix > maxBmpSize then
258 add (addCAF caf srt) rst
260 Nothing -> add (addCAF caf srt) rst
261 (topSRT, subSRTs) <- sub_srt topSRT cafs
262 let (sub_tbls, blockSRTs) = subSRTs
263 return (topSRT, sub_tbls, blockSRTs)
265 -- Construct an SRT bitmap.
266 -- Adapted from simpleStg/SRT.lhs, which expects Id's.
267 procpointSRT :: CLabel -> FiniteMap CLabel Int -> [CLabel] ->
268 FuelMonad (Maybe CmmTopZ, C_SRT)
269 procpointSRT _ _ [] =
270 return (Nothing, NoC_SRT)
271 procpointSRT top_srt top_table entries =
272 do (top, srt) <- bitmap `seq` to_SRT top_srt offset len bitmap
275 ints = map (expectJust "constructSRT" . lookupFM top_table) entries
276 sorted_ints = sortLe (<=) ints
277 offset = head sorted_ints
278 bitmap_entries = map (subtract offset) sorted_ints
279 len = P.last bitmap_entries + 1
280 bitmap = intsToBitmap len bitmap_entries
283 maxBmpSize = widthInBits wordWidth `div` 2
285 -- Adapted from codeGen/StgCmmUtils, which converts from SRT to C_SRT.
286 to_SRT :: CLabel -> Int -> Int -> Bitmap -> FuelMonad (Maybe CmmTopZ, C_SRT)
287 to_SRT top_srt off len bmp
288 | len > maxBmpSize || bmp == [fromIntegral srt_escape]
289 = do id <- getUniqueM
290 let srt_desc_lbl = mkLargeSRTLabel id
291 tbl = CmmData RelocatableReadOnlyData $
292 CmmDataLabel srt_desc_lbl : map CmmStaticLit
293 ( cmmLabelOffW top_srt off
294 : mkWordCLit (fromIntegral len)
295 : map mkWordCLit bmp)
296 return (Just tbl, C_SRT srt_desc_lbl 0 srt_escape)
298 = return (Nothing, C_SRT top_srt off (fromIntegral (head bmp)))
299 -- The fromIntegral converts to StgHalfWord
301 -- Gather CAF info for a procedure, but only if the procedure
302 -- doesn't have a static closure.
303 -- (If it has a static closure, it will already have an SRT to
304 -- keep its CAFs live.)
305 -- Any procedure referring to a non-static CAF c must keep live the
306 -- any CAF that is reachable from c.
307 localCAFInfo :: CAFEnv -> CmmTopZ -> Maybe (CLabel, CAFSet)
308 localCAFInfo _ (CmmData _ _) = Nothing
309 localCAFInfo cafEnv (CmmProc (CmmInfo _ _ infoTbl) top_l _ (_, LGraph entry _)) =
311 CmmInfoTable False _ _ _ ->
312 Just (cvtToClosureLbl top_l,
313 expectJust "maybeBindCAFs" $ lookupBlockEnv cafEnv entry)
316 -- Once we have the local CAF sets for some (possibly) mutually
317 -- recursive functions, we can create an environment mapping
318 -- each function to its set of CAFs. Note that a CAF may
319 -- be a reference to a function. If that function f does not have
320 -- a static closure, then we need to refer specifically
321 -- to the set of CAFs used by f. Of course, the set of CAFs
322 -- used by f must be included in the local CAF sets that are input to
323 -- this function. To minimize lookup time later, we return
324 -- the environment with every reference to f replaced by its set of CAFs.
325 -- To do this replacement efficiently, we gather strongly connected
326 -- components, then we sort the components in topological order.
327 mkTopCAFInfo :: [(CLabel, CAFSet)] -> FiniteMap CLabel CAFSet
328 mkTopCAFInfo localCAFs = foldl addToTop emptyFM g
329 where addToTop env (AcyclicSCC (l, cafset)) =
330 addToFM env l (flatten env cafset)
331 addToTop env (CyclicSCC nodes) =
332 let (lbls, cafsets) = unzip nodes
333 cafset = foldl plusFM emptyFM cafsets `delListFromFM` lbls
334 in foldl (\env l -> addToFM env l (flatten env cafset)) env lbls
335 flatten env cafset = foldFM (lookup env) emptyFM cafset
336 lookup env caf () cafset' =
337 case lookupFM env caf of Just cafs -> foldFM add cafset' cafs
338 Nothing -> add caf () cafset'
339 add caf () cafset' = addToFM cafset' caf ()
340 g = stronglyConnCompFromEdgedVertices
341 (map (\n@(l, cafs) -> (n, l, keysFM cafs)) localCAFs)
343 type StackLayout = [Maybe LocalReg]
345 -- Bundle the CAFs used at a procpoint.
346 bundleCAFs :: CAFEnv -> CmmTopForInfoTables -> (CAFSet, CmmTopForInfoTables)
347 bundleCAFs cafEnv t@(ProcInfoTable _ procpoints) =
348 case blockSetToList procpoints of
349 [bid] -> (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
350 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
351 -- until we stop splitting the graphs at procpoints in the native path
352 bundleCAFs cafEnv t@(FloatingInfoTable _ bid _) =
353 (expectJust "bundleCAFs " (lookupBlockEnv cafEnv bid), t)
354 bundleCAFs _ t@(NoInfoTable _) = (emptyFM, t)
356 -- Construct the SRTs for the given procedure.
357 setInfoTableSRT :: FiniteMap CLabel CAFSet -> TopSRT -> (CAFSet, CmmTopForInfoTables) ->
358 FuelMonad (TopSRT, [CmmTopForInfoTables])
359 setInfoTableSRT topCAFMap topSRT (cafs, t@(ProcInfoTable _ procpoints)) =
360 case blockSetToList procpoints of
361 [_] -> setSRT cafs topCAFMap topSRT t
362 _ -> panic "setInfoTableStackMap: unexpect number of procpoints"
363 -- until we stop splitting the graphs at procpoints in the native path
364 setInfoTableSRT topCAFMap topSRT (cafs, t@(FloatingInfoTable _ _ _)) =
365 setSRT cafs topCAFMap topSRT t
366 setInfoTableSRT _ topSRT (_, t@(NoInfoTable _)) = return (topSRT, [t])
368 setSRT :: CAFSet -> FiniteMap CLabel CAFSet -> TopSRT ->
369 CmmTopForInfoTables -> FuelMonad (TopSRT, [CmmTopForInfoTables])
370 setSRT cafs topCAFMap topSRT t =
371 do (topSRT, cafTable, srt) <- buildSRTs topSRT topCAFMap cafs
372 let t' = updInfo id (const srt) t
374 Just tbl -> return (topSRT, [t', NoInfoTable tbl])
375 Nothing -> return (topSRT, [t'])
377 updInfo :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) ->
378 CmmTopForInfoTables -> CmmTopForInfoTables
379 updInfo toVars toSrt (ProcInfoTable (CmmProc info top_l top_args g) procpoints) =
380 ProcInfoTable (CmmProc (updInfoTbl toVars toSrt info) top_l top_args g) procpoints
381 updInfo toVars toSrt (FloatingInfoTable info bid updfr_off) =
382 FloatingInfoTable (updInfoTbl toVars toSrt info) bid updfr_off
383 updInfo _ _ (NoInfoTable _) = panic "can't update NoInfoTable"
384 updInfo _ _ _ = panic "unexpected arg to updInfo"
386 updInfoTbl :: (StackLayout -> StackLayout) -> (C_SRT -> C_SRT) -> CmmInfo -> CmmInfo
387 updInfoTbl toVars toSrt (CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo))
388 = CmmInfo gc upd_fr (CmmInfoTable s p t typeinfo')
389 where typeinfo' = case typeinfo of
390 t@(ConstrInfo _ _ _) -> t
391 (FunInfo c s a d e) -> FunInfo c (toSrt s) a d e
392 (ThunkInfo c s) -> ThunkInfo c (toSrt s)
393 (ThunkSelectorInfo x s) -> ThunkSelectorInfo x (toSrt s)
394 (ContInfo v s) -> ContInfo (toVars v) (toSrt s)
395 updInfoTbl _ _ t@(CmmInfo _ _ CmmNonInfoTable) = t
397 -- Lower the CmmTopForInfoTables type down to good old CmmTopZ
398 -- by emitting info tables as data where necessary.
399 finishInfoTables :: CmmTopForInfoTables -> IO [CmmTopZ]
400 finishInfoTables (NoInfoTable t) = return [t]
401 finishInfoTables (ProcInfoTable p _) = return [p]
402 finishInfoTables (FloatingInfoTable (CmmInfo _ _ infotbl) bid _) =
403 do uniq_supply <- mkSplitUniqSupply 'i'
404 return $ mkBareInfoTable (retPtLbl bid) (uniqFromSupply uniq_supply) infotbl
406 ----------------------------------------------------------------
407 -- Safe foreign calls:
408 -- Our analyses capture the dataflow facts at block boundaries, but we need
409 -- to extend the CAF and live-slot analyses to safe foreign calls as well,
410 -- which show up as middle nodes.
411 extendEnvsForSafeForeignCalls :: CAFEnv -> SlotEnv -> CmmGraph -> (CAFEnv, SlotEnv)
412 extendEnvsForSafeForeignCalls cafEnv slotEnv g =
413 fold_blocks block (cafEnv, slotEnv) g
415 tail ( bt_last_in cafTransfers l (lookupFn cafEnv)
416 , bt_last_in liveSlotTransfers l (lookupFn slotEnv))
418 where (head, last) = goto_end (G.unzip b)
419 l = case last of LastOther l -> l
420 LastExit -> panic "extendEnvs lastExit"
421 tail _ z (ZFirst _) = z
422 tail lives@(cafs, slots) (cafEnv, slotEnv)
423 (ZHead h m@(MidForeignCall (Safe bid _) _ _ _)) =
424 let slots' = removeLiveSlotDefs slots m
425 slotEnv' = extendBlockEnv slotEnv bid slots'
426 cafEnv' = extendBlockEnv cafEnv bid cafs
427 in tail (upd lives m) (cafEnv', slotEnv') h
428 tail lives z (ZHead h m) = tail (upd lives m) z h
429 lookupFn map k = expectJust "extendEnvsForSafeFCalls" $ lookupBlockEnv map k
430 upd (cafs, slots) m =
431 (bt_middle_in cafTransfers m cafs, bt_middle_in liveSlotTransfers m slots)
433 -- Safe foreign calls: We need to insert the code that suspends and resumes
434 -- the thread before and after a safe foreign call.
435 -- Why do we do this so late in the pipeline?
436 -- Because we need this code to appear without interrruption: you can't rely on the
437 -- value of the stack pointer between the call and resetting the thread state;
438 -- you need to have an infotable on the young end of the stack both when
439 -- suspending the thread and making the foreign call.
440 -- All of this is much easier if we insert the suspend and resume calls here.
442 -- At the same time, we prepare for the stages of the compiler that
443 -- build the proc points. We have to do this at the same time because
444 -- the safe foreign calls need special treatment with respect to infotables.
445 -- A safe foreign call needs an infotable even though it isn't
446 -- a procpoint. The following datatype captures the information
447 -- needed to generate the infotables along with the Cmm data and procedures.
449 data CmmTopForInfoTables
450 = NoInfoTable CmmTopZ -- must be CmmData
451 | ProcInfoTable CmmTopZ BlockSet -- CmmProc; argument is its set of procpoints
452 | FloatingInfoTable CmmInfo BlockId UpdFrameOffset
453 instance Outputable CmmTopForInfoTables where
454 ppr (NoInfoTable t) = text "NoInfoTable: " <+> ppr t
455 ppr (ProcInfoTable t bids) = text "ProcInfoTable: " <+> ppr t <+> ppr bids
456 ppr (FloatingInfoTable info bid upd) =
457 text "FloatingInfoTable: " <+> ppr info <+> ppr bid <+> ppr upd
459 -- The `safeState' record collects the info we update while lowering the
460 -- safe foreign calls in the graph.
461 data SafeState = State { s_blocks :: BlockEnv CmmBlock
462 , s_pps :: ProcPointSet
463 , s_safeCalls :: [CmmTopForInfoTables]}
465 lowerSafeForeignCalls
466 :: [[CmmTopForInfoTables]] -> CmmTopZ -> FuelMonad [[CmmTopForInfoTables]]
467 lowerSafeForeignCalls rst t@(CmmData _ _) = return $ [NoInfoTable t] : rst
468 lowerSafeForeignCalls rst (CmmProc info l args (off, g@(LGraph entry _))) = do
469 let init = return $ State emptyBlockEnv emptyBlockSet []
470 let block b@(Block bid _) z = do
471 state@(State {s_pps = ppset, s_blocks = blocks}) <- z
472 let ppset' = if bid == entry then extendBlockSet ppset bid else ppset
473 state' = state { s_pps = ppset' }
474 if hasSafeForeignCall b
475 then lowerSafeCallBlock state' b
476 else return (state' { s_blocks = insertBlock b blocks })
477 State blocks' g_procpoints safeCalls <- fold_blocks block init g
478 let proc = (CmmProc info l args (off, LGraph entry blocks'))
479 procTable = case off of
480 (_, Just _) -> [ProcInfoTable proc g_procpoints]
481 _ -> [NoInfoTable proc] -- not a successor of a call
482 return $ safeCalls : procTable : rst
484 -- Check for foreign calls -- if none, then we can avoid copying the block.
485 hasSafeForeignCall :: CmmBlock -> Bool
486 hasSafeForeignCall (Block _ t) = tail t
487 where tail (ZTail (MidForeignCall (Safe _ _) _ _ _) _) = True
488 tail (ZTail _ t) = tail t
489 tail (ZLast _) = False
491 -- Lower each safe call in the block, update the CAF and slot environments
492 -- to include each of those calls, and insert the new block in the blockEnv.
493 lowerSafeCallBlock :: SafeState-> CmmBlock -> FuelMonad SafeState
494 lowerSafeCallBlock state b = tail (return state) (ZBlock head (ZLast last))
495 where (head, last) = goto_end (G.unzip b)
496 tail s b@(ZBlock (ZFirst _) _) =
498 return $ state { s_blocks = insertBlock (G.zip b) (s_blocks state) }
499 tail s (ZBlock (ZHead h m@(MidForeignCall (Safe bid updfr_off) _ _ _)) t) =
502 { s_safeCalls = FloatingInfoTable emptyContInfoTable bid updfr_off :
504 (state'', t') <- lowerSafeForeignCall state' m t
505 tail (return state'') (ZBlock h t')
506 tail s (ZBlock (ZHead h m) t) = tail s (ZBlock h (ZTail m t))
509 -- Late in the code generator, we want to insert the code necessary
510 -- to lower a safe foreign call to a sequence of unsafe calls.
511 lowerSafeForeignCall ::
512 SafeState -> Middle -> ZTail Middle Last -> FuelMonad (SafeState, ZTail Middle Last)
513 lowerSafeForeignCall state m@(MidForeignCall (Safe infotable _) _ _ _) tail = do
514 let newTemp rep = getUniqueM >>= \u -> return (LocalReg u rep)
515 -- Both 'id' and 'new_base' are KindNonPtr because they're
516 -- RTS-only objects and are not subject to garbage collection
518 new_base <- newTemp (cmmRegType (CmmGlobal BaseReg))
519 let (caller_save, caller_load) = callerSaveVolatileRegs
520 load_tso <- newTemp gcWord -- TODO FIXME NOW
521 let suspendThread = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "suspendThread")))
522 resumeThread = CmmLit (CmmLabel (mkRtsCodeLabel (sLit "resumeThread")))
523 suspend = mkStore (CmmReg spReg) (CmmLit (CmmBlock infotable)) <*>
526 mkUnsafeCall (ForeignTarget suspendThread
527 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
528 [id] [CmmReg (CmmGlobal BaseReg)]
529 resume = mkUnsafeCall (ForeignTarget resumeThread
530 (ForeignConvention CCallConv [AddrHint] [AddrHint]))
531 [new_base] [CmmReg (CmmLocal id)] <*>
532 -- Assign the result to BaseReg: we
533 -- might now have a different Capability!
534 mkAssign (CmmGlobal BaseReg) (CmmReg (CmmLocal new_base)) <*>
536 loadThreadState load_tso
537 Graph tail' blocks' <-
538 liftUniq (graphOfAGraph (suspend <*> mkMiddle m <*> resume <*> mkZTail tail))
539 return (state {s_blocks = s_blocks state `plusBlockEnv` blocks'}, tail')
540 lowerSafeForeignCall _ _ _ = panic "lowerSafeForeignCall was passed something else"